A conventional image forming apparatus is configured such that, upon occurrence of paper jam in a roller for conveying a recording sheet (conveying roller), a drive motor is driven in a reverse rotation to drive each gears of gear transmission mechanism in the reverse rotation, and thereby separating a middle gear (planetary gear) from a gear at a position downstream thereof (idle gear) to cut off transmission of a driving force. With this configuration, the conveying roller can be freely rotated after the drive motor has been driven in the reverse rotation. Hence, the paper jam can be easily resolved.